Heated towers, reactors, drums, tanks, pipes, vessels, and the like (hereinafter “heated vessels”) are used in many manufacturing processes. A coker unit, for example, is a form of drum or tank used to convert residual oil from a distillation column of an oil refinery into low molecular weight hydrocarbon gases, naphtha, light and heavy gas oils, and petroleum coke. A coker unit typically operates by thermally cracking the long chain hydrocarbon molecules in the residual oil feed into shorter chain molecules by heating the residual oil up to about 480 degrees Celsius over a 14-20 hour period.
Many heated vessels utilized in manufacturing are thermally isolated through the use of external insulation systems. These external insulation systems may comprise a mineral fiber or a ceramic material (e.g., calcium silicate) that is applied directly to the outside of the heated vessel and fixated thereon with wire or stainless steel banding. An external jacket is then frequently applied to protect the insulation from moisture and other ambient conditions. Nevertheless, while such external insulation systems are in widespread use, they suffer from several disadvantages. One such disadvantage is the possibility of “corrosion under insulation” (CUI). In CUI, water condensation occurs on the vessel under the insulation. Corrosion of the vessel is thereby enhanced. Another disadvantage of currently implemented external insulation systems relates to fatigue cracking. Many heated vessels are formed of low alloy steels that are vulnerable to forming fractures as a result of repeated thermal cycling. Numerous coker units, for example, have been found to exhibit fatigue cracks after a few thousand heating cycles. Accordingly, as a result of both CUI and fatigue cracking, most heated vessels must be inspected on a regular basis to determine vessel integrity. Where issues are found, repairs must be performed. Unfortunately, currently available external insulation systems do not facilitate this kind of inspection and maintenance. Instead, large portions of the external insulation system typically must be removed to gain access to the underlying heated vessel, consuming both time and manpower while the heated vessel is out of service.
For at least the foregoing reasons, there is therefore a need for new external insulation systems that facilitate both the localized inspection and maintenance of heated vessels. Ideally, such new external insulation systems will also be easy to install, provide excellent thermal isolation, allow adequate thermal expansion and contraction of the underlying heated vessels, be effective barriers to the intrusion of water and other atmospheric elements, and be cost effective.